Waterproofing coatings are frequently applied to the outer surface of concrete foundation walls to prevent water penetration through the wall. An extremely effective waterproofing coating is that described in U.S. Pat. No. 5,352,531. The coating of that patent is a highly adhesive, elastomeric type which is asphalt free and is non-hazardous and non-toxic when cured. The coating when applied to a foundation wall provides an adhesive, water impervious membrane that prevents penetration of water through the wall, even when the wall is subjected to substantial hydrostatic pressure.
To prevent damage to the elastomeric coating when the wall is back-filled through the use of mechanical handling equipment, it has been the practice to apply protection board over the elastomeric coating. A common type of protection board, as used in the past, is polystyrene foam board. The polystyrene board aids in protecting the elastomeric coating and has some insulating value. However, the polystyrene foam can be fractured by back-filling and is not waterproof. Over time the polystyrene foam will absorb water, and in itself does not constitute a waterproofing membrane.
U.S. Pat. No. 5,857,297 describes an improved waterproofing system for a backfilled foundation wall, in which an extruded, rigid, thermoplastic protection board is applied over the elastomeric coating on the foundation wall. The protection board, as described in U.S. Pat. No. 5,857,297, includes an inner face which is bonded to the elastomeric coating and a parallel outer face. A plurality of spaced ribs interconnect the two faces and define a plurality of vertical flow channels which extend the entire height of the board. A series of openings, slots or holes are formed in the outer face of the board and communicate with the flow channels. Water from the soil can enter the openings and flow downwardly through the flow channels to the drain tile, thus draining the water as well as relieving hydraulic pressure against the wall.
With the waterproofing system as described in U.S. Pat. No. 5,857,297, the elastomeric coating applied to the foundation wall is extremely tacky or adhesive and if the protection boards are not properly aligned in side-by-side relation, it is very difficult to remove or shift the boards. When this happens, it is necessary to seal the joints between adjacent vertical edges of the boards by caulking or sealing tape, or re-cut new boards for proper alignment. This manual joint sealing or re-cutting operation requires considerable time and labor.